This invention relates generally to methods, systems, and compositions for removing mercury from combustion gas, and, more specifically, to methods, systems, and compositions for removing mercury in flue gas from coal-fired processes.
Volatile metals such as mercury (Hg) are among several air pollutants produced by combustion processes. The U.S. EPA has determined that Hg emissions from power plants must be reduced. Many utilities are actively seeking effective and inexpensive technologies to control Hg emissions.
Presently, there are several technologies available that remove mercury and other substances. For example, injecting activated carbon into the flue is one of the most developed and researched methods for reducing mercury from coal-fired flue gas. Depending on the specific configuration and coal type, the efficiency of Hg removal by activated carbon injection ranges from 40% to 90%. However, the cost of mercury control using activated carbon injection can be very high ranging from $8,000 to $70,000 per lb Hg removed.
Furthermore, due to numerous factors, including the composition of the fuel, the combustion process, the configuration of the power plant, and the number and variety of substances to reduce, no single available control technology can provide effective mercury reduction for all applications. Thus, alternatives for removing mercury and other substances are desired.